Door with automatic fire restricting system

ABSTRACT

In response to detection of fire, electronic means controls overload sensitive closing of a door to a protected space. The door remains closed for a short warning period and is then partially opened automatically for a predetermined period to permit escape of persons from the protected space. Upon final closing of the door, fire extinguishing means are operated within the protected space.

United States Patent [1 1 Smart [451 Apr. 30, 1974 4] DOOR WITHAUTOMATIC FIRE 2,841,389 7/1958 Litherland 49/27 RESTRICTING SYSTEM3,599,371 8/1971 Barroero 49/30 3,509,934 5/1970 Smart 160/84 R [75']Inventor: Jay A. Smart, Salt Lake City, Utah. 3,720,254 3/ 1973 Smart160/84 R [73] Assignee: Won-Door Corporation, Salt Lake City, UtahPrimary Examiner-Peter M. Caun Attorney, Agent, or Firm-Clarence A.OBrien; Har- [22] Flled. May 23, 1972 vey B Jacobson [21] Appl. No.:256,130 1 I [57] ABSTRACT [52] US. Cl. 160/1 In response to detection 6ffire, electronic means com [51] Int. Cl E05f 15/20 trols overloadsensltlve closlng of a door to a pro- [58] Fleld of Search 160/1, 5, 6,84 R, d 1 Th d l d f h 49/27 30 tecte spao e. e 00! remains cose or a sort Y warmng penod and 1s then partially opened automati- [56]References Cited cally for a predetermined perrod to permlt escape ofpersons from the protected space. Upon final closlng UNlTED STATESPATENTS i of the door, fire extinguishing means are operated 3,337,9928/1967 Tolson 49/29 within the protected space, 2,678,212 5/1954Flostroy... 2,871,009 H1959 Picatti 49/30 f 13 Claims, Drawing Figures f:2 \vs 0-34 a4- I o o o a; l I I 30 3a E 2a I Door way Pulley Drive I:Sys!em 38 r E/EC/IO' l mag/relic N c/u/m 42 [I r 555%" I DC Molar 44{-24 2" Electron/c i i Carma/s J l "f S S I Lead Pas! PMEWEBAPRW awzmalmso Fig Lead Pas? This invention relates to automatic closureoperating systems and more particularly to a door closing and openingsystem that is programmed for fire emergency purposes.

. An important object of the present invention is to provide anautomatic control system for a power operated, fireproof door wherebyopening and closing of the door to a space protected by a fire sensingand fire extinguishing system, may be closed off in order to isolate andextinguish the fire and yet enable any persons trapped in such space toescape without injury. Such a door operating system requires differentdoor closing and opening modes as well as timing in order to meet fireemergency conditions. The system of the present invention thereforecombines the qualities of a fireproof door with automatic door operationand actuation of fire extinguishers whereby fire may be isolated orcontained, extinguished and yet allow rapid and panic-free evacuation.

by a header 22 and a female jamb 24. The passageway 12 is adapted to beclosed by a fireproof closure device or door generally referred to byreference numeral 26 of a typedisclosed for example in my prior US. Pat.No. 3,509,934. The door 26 is adapted to be closed or opened'by poweroperating mechanism generally referred to by reference numeral 28through a cable systern that extends from the power operating mechanismwhich is positioned, for example, adjacent to the wall 16. The cableextends through the upper frame member 30 on top of the accesspassageway 12 and into the jamb 24 adapted to be engaged by the leadpost 32 of the door in its fully closed position.

- The installation shown in FIG. 1 is adapted to be associated with aprotected enclosure or space within which fire sensing devices aremounted such as ionization type smoke detectors. These fire detectingsystems i are well known, the details of which form no part of the Inaccordance with the present invention, any conpersons attempting toescape during this operational phase. When the door is fully closed, atimer controlled mode of operation ensues during which the door ispartially opened and then closed for a predetermined period of time. Thetimer-controlled partial opening and closing operation is repeated atleast two times in order to permit persons to evacuate the space throughthe access opening within which the door is installed. Upon finalclosing of the door, fire extinguishers are triggered into operationwithin the protected space. Automatic control may be overridden at anytime by a manual operational mode wherein the door is selectively openedat any time. The electronic controls through which automatic orsemi-automatic operation is effected, operate on the doors through apower operated drive mechanism featuring an electromagnetic clutch thatis deenergized whenever the door is at rest in order to prevent damageto the drive mechanism and permit manual override.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

FIG. 1 is a front elevational view of an access region associated with aprotected space wherein the closure andthe automatic operating system ofthe present invention is installed.

FIG. 2 is a functional block diagram illustrating the control system ofthe present invention. 1

FIG. 3 is an electrical circuit diagram corresponding to the controlsystem of FIG. 2.

Referring now to the drawings in detail, FIG. ll illustrates a typicalinstallation for the present invention generally referred to byreference numeral 10. As shown in FIG. 1, an access passageway 12 to andfrom a protected enclosure or space within a building is defined betweenvertical walls 14 and 16, a ceiling l8 and floor 20. The accesspassageway is furthermore framed present invention. Further, such firedetecting systems are often associated with fire extinguishingfacilities. In the installation shown in FIG. 1, by way of example,nozzles 34 may be mounted on the header 22 from which fire extinguishingmedium may be discharged in spray form into the protected space forextinguishing any fire after it is confined to said space by closing ofthe door 26 to seal the space.

Before the protected space is sealed, and the fire extinguishing meanstriggered into operation, the door 26 is operated in such a fashion asto provide a warning and permit evacuation of the protected space. Thus,closing and opening operation of the door is effected by means of thepower operating mechanism 28 in an automatic fashion with manualoverride. As hereinbefore indicated, movement of the door is closing andopening directions is imparted by the power operating mechanism throughthe cable system which includes cables 36 associated with a pulley drivearrangement generally referred to by reference numeral 38 that isdrivingly connected to the output of a reduction gear assembly 40through an electromagnetically operated clutch device 42. A reversibleDC motor 44 drives the reduction gear assembly 40. An electronic controlassembly generally referred to by reference numeral 46 controlsoperation of the motor 44 and the electromagnetic clutch 42. r

FIG. 2 diagrammatically. illustrates the electronic control assemblywhich is operative to energize the motor 44, the motor being in turndrivingly connected through the clutch device 42 to the pulley drivesystem 38. The control assembly is connected to a DC source ofelectrical energy by means of positive and negative voltage lines 48 and50. A power regulator 52 is connected across the 'voltage lines forsupplying a reduced DC voltage to some of the components in the controlassembly. The motor 44 is connected to the power supply through thevoltage lines 48 and 50 in series with a high current switch component54 and a high current sensor component 56 through a reversing switchassembly 58 by means of which the direction of rotation of the motor isselected in order to effect either closing or opening movement of thedoor. Actuation of the reversing switch assembly 58 and selection of themotor direction, is effected through a drive control component 60 towhich drive producing signals are fed from a pair of control logics 62and 64 respectively operative to effect closing an opening operation.The close logic 62 and open logic 64 are respectively triggered intooperation by signals supplied thereto from a gate circuit 66.Alternatively, the close and open logics 62 and 64 may be triggered intooperation manually by actuation of switches 68 and 70 respectivelyconnecting the logics to the negative voltage line 50.

The high current switch component 54 is normally rendered operativewhenever the reversing switch assembly 58 is supplying energy to themotor to remain conductive regardless of the load condition on the motorand thus maintain the motor energized. A load control component 72 isconnected to the high current switch assembly 54 in order to render thehigh current switch assembly sensitive to overload conditions on themotor resulting in the opening of the switch assembly 54 andde-energization of the motor momentarily during a logic controlled phaseof operation. This phase of operation is initiated by a signal from afire detector 74 of the type aforementioned. The fire detector isconnected through a latching switch component 76 to an automaticrepetitive close logic 78 that generates operating pulses transmitted bythe gate circuit 66 to the close logic 62 during the logic controlledphase of operation. Whenever a signal is initially fed to the closelogic 62 to initiate closing of the door, a signal is also fed todisable logic 80 through which a disable signal is fed to the loadcontrol component 72 in order to render the high current switch assembly54 temporarily insensitive to motor overload during the logic controlledphase of operation for starting purposes.

During the logic controlled phase of operation, the door begins to closebut whenever it meets an obstruction, its movement is momentarilyarrested. After a short delay, closing is again attempted. When the dooris fully closed, the logic controlled phase of operation is terminatedby a limit switch 82 actuated by the lead post of the door engaging thejamb 24, for example. Actuation of the limit switch 82 triggers intooperation the timer component 84. Also, during the logic controlledphase of operation, each time the movement of the door is arrested, themotor is de-energized whereupon the clutch 42 is also de-energized so asto isolate the door drive from the motor while at rest.

During the foregoing logic-controlled phase of opera tion, a warningperiod is established by the closing of the door without any possibleinjury to persons attempting to enter or exit the passageway. When thewarning period is completed upon sealing of the protected space byclosing of the door fully, a timercontrolled operational phase isinitiated beginning with a three second delay before partial opening ofthe door is effected in response to a signal fed to the open logic 64from the timer through the gate circuit 66. During the timer-controlledphase of operation, sensor component 56 is operative through the loadcontrolled component 72 to render the high current switch assembly 54insensitive to overload of the motor so that the motor will remainenergized until the door is partially opened to a predetermined extentat which time the motor is de-energized and the door remains partiallyopened for a preset period of time determined by the timer 84. The doorthen closes in response to a signal supplied to the close logic by thetimer through the gate circuit 66. The door remains fully closed for aninterval of about five seconds after which it opens partially again fora shorter preset period determined by the timer 84. Finally, the door isfully closed under control of the timer and the first extinguishercomponent 86 triggered into operation.

FIG. 3 illustrates in greater detail the control system. The highcurrent switch assembly 54 as shown includes a triac 88 having its anodeconnected to the positive voltage line 48 and its cathode connected byline 90 to the motor control circuit 58. Thus, the triac 88 is connectedin series with the motor load 44 when the motor control circuit iscompleted. Also connected in series with the motor load is the resistor92 of the high current sensor 56 interconnected between the motor andthe negative voltage line 50. Under normal load conditions, the voltagedrop across the anode and cathode of the triac 88 exceeds break-overvoltage value so that the triac conducts and enables operation of themotor. Under overload conditions, however, the voltage across the anodeand cathode of the triac is below break-over value which would cause thetriac to switch off unless a positive voltage is applied to its gatefrom the positive voltage line 48 through the gate control resistor 94upon closing of a normally open relay switch 96. The voltage applied tothe gate of the triac is regulated by the resistors 98 and 100interconnected by the diode 102 between the gate and the negativevoltage line 50. The relay switch 96 is closed in response toenergization of a relay coil 104 that may be energized whenever themotor control circuit is activated. Thus, the motor will not start ifthere is any initial overload but may remain energized should anyoverload occur thereafter.

The motor control circuit includes a door closing relay coil 106energized in response to a drive signal output from the drive controlcomponent 60 connected to the relay coil 106 through diode 108. Uponenergization of the relay coil 106, the relay switch 110 is actuated inorder to connect the voltage line 90 to one terminal of the motor 44through line 112 while the other motor line 114 is connected, by closingof the normally opened relay switch 116, to the negative voltage line 50through the resistor 92. Normally opened relay switch 118 is also closedin response to energization of the relay coil 106 in order to completean energizing circuit through the gate controlling relay coil 104 inseries with resistor 120 and diode 122. Thus, relay coil 104 may beenergized simultaneously with relay coil 106 in order to initiateoperation of the motor in a closing direction. Similarly, operation ofthe motor may be initiated in an opening direction by energization ofthe relay coil 124 in the motor control circuit to close the normallyopened relay switch 126 thereby also completing an energizing circuitfor the relay coil 104 in the high current switch assembly in serieswith the resistor 120 and diode 128. The door opening output of thedrive control component 60 is therefore connected to the diode 128-andthrough diode 130 to the relay coil 124 for energization thereof. Whenenergized, the relay coil 124 also actuates the relay switch 132 and thenormally opened relay switch 134 in order to establish a reverseconnection between the voltage lines and the motor terminal lines 112and 114 for opening operation of the motor.

The drive control component 60 is connected to the relay coils 106 and124 through a pair of output lines 136 and 138 respectively connected tothe output collectors of transistors 140 and 142 having their emittersconnected to the positive voltage line 48. The bases of transistors 140and 142 are respectively connected by 'base resistors 144 and 146 to theoutput collectors of signal transistors 148 and 150. The collectors ofthe transistors 148- and 150 are connected to the positive voltage line48 through load resistors 152 and 154. The signal transistors 148 and150 which are normally nonconductive, are switched on by signalsrespectively applied to the bases thereof from the close logic 62 andciated relay coil 106 or 124 in the motorcontrol circuit.

The energizing circuit established-for the relay coil 104 in thehighcurrent switch assembly 54, by closing ofeither, of thenormally'openrelay switches 118 and 1 26, may be shunted by switching on of asemiconductor controlled rectifier (SCR) 1-56 in the load controlcomponent 72. The SCR 156 has its anode connected to the juncturebetween resistor 158 and the diode 1 59 interconnected between theresistor 120and the positive voltage line 48. Thus, the voltage acrossthe anode and cathode of the SCR 156 is held below break-over value. TheSCR 156 may, however, be

switched on by trigger voltage supplied to its gate from the highcurrent sensor 56 which includes an adjustable potentiometer 162 andresistor 160 connected in series sistor 92. Conductor 164 interconnectsthe juncture between the potentiometer 162 and the resistor 160 with thegate of the SCR 156 in order to apply a reduced positivevoltage to thegate that will switch on the SCR under normal load conditions of. themotor. When switched on, the SCR 156 will prevent energization of therelay coil 104 so that the triac 88 will respond to any overload of themotor and switch off. However, below excessive overload conditions, thevoltage supplied by the sensor 56 to the gate of SCR 156 will be below'trigger value. Accordingly, the SCR 156 will switch off and relay coil104 will be energized to prevent thetriac 88 from switching off becauseof the positive voltage applied to its gate through the relay switch 96.Thus, the sensor 56 operates through the SCR 156 on the load controlcomponent 72 to establish operational limits for the triac 88 causing itto open only in response to excessive overload but not in response tooverload occasioned by relatively small obstructions.

During the logic controlled operational phase, the SCR 156 is initiallydisabled in order to permit energization of the relay coil 104 andmomentarily render the triac 88 insensitive to overload conditions-so asto ensure starting of the motor. Toward this end, a reverse bias isapplied to the anode of the SCR 156 by closing of the'normally openrelay switch 162 connecting the anode of the SCR 156' to the negativevoltage line 50. Relay switch 163 is closed by energization of relaycoil 165 in response to a pulse supplied thereto from the collector ofsignal transistor 166 having its base com nected to the output ofdisable logic 80. The SCR 156 is switched off during the timercontrolled operational phase by connecting the gate to the negativevoltage line 50- upon closing of the normally open relay switch 168 uponenergization of the relay coil 170 connected to the timer component 84.At the end of an operational cycle, the SCR 156 is again switched on bya pos- 6 itive trigger voltage supplied to its gate through diode 172from the timer component 84.

Each of the control logics 62, 64 and 80 are similar in operation andarrangement. Each is operative when supplied with a trigger signal todeliver a pulse of predetermined duration to its signal output. Thus,the close logic supplies a pulse of sufficient duration to the base oftransistor 148 in the drive control component through the line 174 inorder to initiate closing movement of the door while the output line 176from the open logic 64 supplies a pulse of sufficient duration to thebase of transistor 150 in order to initiate opening operation. A pulseof shorer duration is supplied by the disable logic 80 to the 'base oftransistor 166 through the line178 to momentarily render the triac 88insensitive to motor overload as aforementioned. The disable logic 80 istriggered into operation each time an activating signal is applied tothe input of the close logic 62 through activating signal line 180.Similarly, the disable logic is activated by an activating signalsimultaneously applied thereto when the open logic 64 is activated by asignal in line 182. The duration of the output pulse of each of thecontrol logics is determined by a capacitor 184 associated with eachcontrol logic having one side thereof connected to the negative voltageline 50.

As shown in FIG. 3, each of the control logics ineludes four NAND gates186, 188, 190 and 192, the

relation to each other and in parallel relation to the refirst gate 186having three inputs, one of which is connected to the activating signalline 180 or 182 and another of which is connected to the manualactivating switch 68 or 70 insofaras the control logics 62 and 64 areconcerned. In the case of disable logic 80, both of the aforementionedinputs of the first gate 186 are connected to the activatingsignal lines180 and 182. Either of the aforementioned inputs may trigger operationof the control logic. The intermediate input of the first gate 186 isconnected to the output of the third gate 190 which is alsointerconnected with the input of the last gate 192. The output of gate186' is interconnected with one of the inputs of each of the gates 188and 190, the other input of gate 188 being connected to the positiveside of capacitor 184 at thejuncture between the capacitor and diode 194interconnecting the capacitor with the output of gate 186. As a resultof this arrangement, a positive cut-off voltage is maintained at theoutput of the last gate 192 in its inactive state so that an inputsignal produces a negative output pulse of predetermined duration asaforementioned.

Activating signals for the control logics through signal lines 180 and182 are respectively supplied from the outputs of close gate 196 andopen gate 198 in the gate circuit 66. One of the inputs in each of thegates is connected by lines 200 and 202 to the timer component 84 inorder to control closing and opening operation during the timercontrolled operational phase as aforementioned. The other inputs of thegates. 196 and 198 are interconnected with the output line 204 from theautomatic repetitive close signal logic 78 which in its inactive statemaintains a positive voltage on the interconnected inputs of the gates196 and 198.

The output line 204 is connected to the output of flip-flop 206 in theclose signal logic 78 and is also interconnected with the input of theother flip-flop 210. The output of flip-flop 210 is connected throughthe inverted OR gate 212 to the input of flip-flop 206. Theflip-flops'206 and 210 are simultaneously toggled by a signal suppliedthereto from the latching switch component 76 through line 214. Each ofthe flip-flops 206 and 210 furthermore includes a pair of terminalsinterconnected by capacitors 216 and connected by resistors 218 to thelow DC voltage supply from the regulator 52. Accordingly, when triggeredinto operation by an output signal in line 214, the close signal logic78 produces an output pulse of predetermined duration and frequency foreffecting closing operation during the logic controlled phase ofoperation. Operation of the close signal logic 78 is however inhibitedduring the timer controlled phase of operation by an inhibit gate 220interconnecting the line 214 with the juncture between the resistor 100and the diode 102. An inhibit signal is supplied to line 214 whentrigger voltage is supplied through the relay switch 96 to the gate oftriac 88 for rendering the triac insensitive to overload during timercontrolled operation as aforementioned.

The flip-flops 206 and 210 are rendered operative by the output in line214 from the latching switch component 76 which includes the gates 222,224 and 226. The output of gate 226 is connected to the output line 214while its input is interconnected between the output of gate 222 and oneof the inputs of gate 224. The other input of gate 224 is connected tothe fire detector component 74 by means of which the latching switchassembly is switched on. The switch assembly is switched off by a resetpulse connected to one of the inputs of gate 222 to which the negativeline 50 is connected by the capacitor 228, the other input of gate 222being connected to the output of gate 224.

It willbe apparent from the foregoing description, that the controlsystem is operative in a logic controlled mode during a warning periodto automatically effect door closing operation with momentary arrest ofthe movement of the door in response to obstructions. The warning periodis followed by a timer controlled evacuation period during whichrepeated opening and closing of the door-occurs without sensitivity toobstructions. Final closing of the door initiates operation of fireextinguishers. Manualoverride of the system is provided by means of theswitches 68 and 70 providing an activating signal to the close and openlogics 62 and 64 in order to effect either closing or opening of thedoor whenever desired.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed and accordingly all suitable modifications and equivalents maybe resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In combination with a closure device and power operating means forclosing and opening the closure device, signal triggered logic meansconnected to the power operating mechanism for only closing the closuredevice during a warning period, and timercontrolled means connected tothe power operating means for repeatedly opening and closing the closuredevice during an evacuation period following the warning period, saidclosure device being installed in an access passageway to an enclosedspace, fire detecting means mounted within said space for triggering thelogic means, and fire extinguishing means mounted within said space foroperation in response to sealing of the space by the closure device upontermination of the evacuation period.

2. The combination of claim 1 including a source of electrical energyfor energizing the power operating mechanism, load sensing switch meansconnecting the source to the power operating mechanism for energizationthereof below overload conditions, and load control means connected tothe switch means for preventing disconnection of source from the poweroperating mechanism in response to overload conditions during theevacuation period.

3. The combination of claim 2 wherein the logic means includes a pair ofcontrol logic devices connected to the power operating mechanism forrespectively efiecting closing and opening of the closure device, pulsegenerating means connected to one of the control logic devices forperiodically triggering closing operation of the closure device duringsaid warning period and disable means connected to the control logicdevices and the load'control means for initially rendering the switchmeans insensitive to overload conditions upon triggering of saidoperation of the closure device.

4. The combination of claim 3 wherein the power operating mechanismincludes a motor connected in series with the switch means to thesource, and electrically operated clutch means disengaging the motor inresponse to opening of the switch means.

5. The combination of claim 4 wherein said switch means includes a triachaving a gate and relay means for supplying trigger voltage to the gatein response to energization of the power operating mechanism to preventthe triac from switching off under the overload conditions.

6. The combination of claim 5 wherein said load control means includesadjustable means for disabling the relay means during said evacuationperiod.

7. The combination of claim 6 wherein said timercontrolled meansincludes gate means for simultaneously disconnecting the pulsegenerating means from said one of the control logic devices andsupplying a triggering signal to the other of the control logic devices.

8. In combination with a closure device and power operating means forclosing and opening the closure device, signal triggered logic meansconnected to the power operating mechanism for only closing the closuredevice during a warning period, timer-controlled means connected to thepower operating means for repeatedly opening and closing the closuredevice during an evacuation period following the warning period, asource of electrical energy for energizing the power operatingmechanism, load sensing switch means connecting the source to the poweroperating means for energization thereof below overload conditions, andload control means connected to the, switch means for preventingdisconnection of the source from the power operating mechanism inresponse to overload conditions during the evacuation period.

9. The combination of claim 8 wherein said switch means includes a triachaving a gate and relay means for supplying trigger voltage to the gatein response to energization of the power operating mechanism to preventthe triac from switching off under the overload conditions.

- control logic devices for periodically triggering closing operation ofthe closure device during said warning period and disable meansconnected to the control logic devices and the load control means forinitially rendering the switch means insensitive to overload conditionsupon triggering of said operation of the closure device.

12. The combination of claim 11 wherein said timercontrolled meansincludes gate means for simultaneously disconnecting the pulsegenerating means from said one of the control logic devices andsupplying a triggering signal to the other of the control logic devices.

13. In combination with a closure device and a power operating mechanismfor closing and opening the closure device. a sensor, logic meansconnected to the sensor and the power operating mechanism for closingthe closure device during a warning period in response to detection of apredetermined condition by said sensor, and timer-controlled meansconnected to the logic means and rendered operative upon closing of theclosure device for repeatedly opening and closing the closure deviceduring an evacuation period following the warning period, said logicmeans including a control logic device for effecting closing operationof the closure device, drive control means connecting the control logicdevice to the power operating mechanism for periodically initiating saidclosing operation during the warning period, overload sensing means formomentarily disabling the power operating mechanism in response toexcessive loading of the closure device during said closing operation,and means for disabling the overload sensing means during the evacuationperiod.

1. In combination with a closure device and power operating means forclosing and opening the closure device, signal triggered logic meansconnected to the power operating mechanism for only closing the closuredevice during a warning period, and timer-controlled means connected tothe power operating means for repeatedly opening and closing the closuredevice during an evacuation period following the warning period, saidclosure device being installed in an access passageway to an enclosedspace, fire detecting means mounted within said space for triggering thelogic means, and fire extinguishing means mounted within said space foroperation in response to sealing of the space by the closure device upontermination of the evacuation period.
 2. The combination of claim 1including a source of electrical energy for energizing the poweroperating mechanism, load sensing switch means connecting the source tothe power operating mechanism for energization thereof below overloadconditions, and load control means connected to the switch means forpreventing disconnection of source from the power operating mechanism inresponse to overload conditions during the evacuation period.
 3. Thecombination of claim 2 wherein the logic means includes a pair ofcontrol logic devices connected to the power operating mechanism forrespectively effecting closing and opening of the closure device, pulsegenerating means connected to one of the control logic devices forperiodically triggering closing operation of the closure device duringsaid warning period and disable means connected to the control logicdevices and the load control means for initially rendering the switchmeans insensitive to overload conditions upon triggering of saidoperation of the closure device.
 4. The combination of claim 3 whereinthe power operating mechanism includes a motor connected in series withthe switch means to the source, and electrically operated clutch meansdisengaging the motor in response to opening of the switch means.
 5. Thecombination of claim 4 wherein said switch means includes a triac havinga gate and relay means for supplying trigger voltage to the gate inresponse to energization of the power operating mechanism to prevent thetriac from switching off under the overload conditions.
 6. Thecombination of claim 5 wherein said load control means includesadjustable means for disabling the relay means during said evacuationperiod.
 7. The combination of claim 6 wherein said timer-controlledmeans includes gate means for simultaneously disconnecting the pulsegenerating means from said one of the control logic devices andsupplying a triggering signal to the other of the control logic devices.8. In combination with a closure device and power operating means forclosing and opening the closure device, signal triggered logic meansconnected to the power operating mechanism for only closing the closuredevice during a warning period, timer-controlled means connected to thepower operating means for repeatedly opening and closing the closuredevice during an evacuation period following the warning period, asource of electrical energy for enerGizing the power operatingmechanism, load sensing switch means connecting the source to the poweroperating means for energization thereof below overload conditions, andload control means connected to the switch means for preventingdisconnection of the source from the power operating mechanism inresponse to overload conditions during the evacuation period.
 9. Thecombination of claim 8 wherein said switch means includes a triac havinga gate and relay means for supplying trigger voltage to the gate inresponse to energization of the power operating mechanism to prevent thetriac from switching off under the overload conditions.
 10. Thecombination of claim 9 wherein said load control means includesadjustable means for disabling the relay means during said evacuationperiod.
 11. The combination of claim 8 wherein the logic means includesa pair of control logic devices connected to the power operatingmechanism for respectively effecting closing and opening of the closuredevice, pulse generating means connected to one of the control logicdevices for periodically triggering closing operation of the closuredevice during said warning period and disable means connected to thecontrol logic devices and the load control means for initially renderingthe switch means insensitive to overload conditions upon triggering ofsaid operation of the closure device.
 12. The combination of claim 11wherein said timer-controlled means includes gate means forsimultaneously disconnecting the pulse generating means from said one ofthe control logic devices and supplying a triggering signal to the otherof the control logic devices.
 13. In combination with a closure deviceand a power operating mechanism for closing and opening the closuredevice, a sensor, logic means connected to the sensor and the poweroperating mechanism for closing the closure device during a warningperiod in response to detection of a predetermined condition by saidsensor, and timer-controlled means connected to the logic means andrendered operative upon closing of the closure device for repeatedlyopening and closing the closure device during an evacuation periodfollowing the warning period, said logic means including a control logicdevice for effecting closing operation of the closure device, drivecontrol means connecting the control logic device to the power operatingmechanism for periodically initiating said closing operation during thewarning period, overload sensing means for momentarily disabling thepower operating mechanism in response to excessive loading of theclosure device during said closing operation, and means for disablingthe overload sensing means during the evacuation period.